前言

在做一个需要Java后台生成大量的XML文件，上传到FTP服务器上，然后另外一个线程连上FTP一直查询上传的文件夹里面有多少个文件，并把文件名通过WebSocket带到页面上更新页面，同时也可以从FTP服务器上下载文件。。。。。

刚开始认为很简单，用Apache的工具FTPClient来做，结果连接不上FTP服务器，后来发现是我们的FTP服务器只支持SFTP协议。

上代码

最开始走的Ftp协议

package com.lucent.demo.utils;

import org.apache.commons.net.ftp.FTPClient;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @author zhangxingrui
 * @create 2018-10-31 9:59
 **/
public class FtpUtil {

    private static final Logger logger = LoggerFactory.getLogger(FtpUtil.class);

    /**
     * 以用户的姓名为key，FTPClient为对象保存起来
     */
    private static Map<String, FTPClient> clients = new ConcurrentHashMap<>();

    public static boolean login(String host, int port, String username, String password, String userId){
        boolean isOk = false;
        FTPClient ftpClient = new FTPClient();
        try {
            ftpClient.setControlEncoding("GBK");
            ftpClient.connect(host, port);
            isOk = ftpClient.login(username, password);
            ftpClient.setFileType(FTPClient.BINARY_FILE_TYPE);
            ftpClient.setBufferSize(1024 * 2);
            ftpClient.setDataTimeout(30 * 1000);
            clients.put(userId, ftpClient);
        } catch (IOException e) {
            logger.error(e.getMessage());
        }
        return isOk;
    }

    public static void logout(String userId){
        if(!clients.containsKey(userId))
            return;

        FTPClient ftpClient = clients.get(userId);
        if(!ftpClient.isConnected())
            return;

        try {
            // 退出FTP服务器
            ftpClient.logout();
        } catch (IOException e) {
            logger.error(e.getMessage());
        } finally {
            try {
                // 关闭FTP服务器连接
                ftpClient.disconnect();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }



}

考虑到要做一个通用的工具，所以我们的程序应该对用户输入的FTP地址进行协议的判断，然后确定要用FTP还是SFTP。

package com.lucent.demo.utils;

import alu.mtosi.common.util.SftpChannel;
import com.jcraft.jsch.ChannelSftp;
import com.jcraft.jsch.JSchException;
import com.lucent.demo.config.GeneralConstant;
import com.lucent.demo.domain.Ftp;
import javafx.util.Pair;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @author zhangxingrui
 * @create 2018-10-31 9:59
 **/
public class SftpUtil {

    private static final Logger logger = LoggerFactory.getLogger(SftpUtil.class);

    private static Map<String, Pair<SftpChannel, ChannelSftp>> map = new ConcurrentHashMap<>();

    public static ChannelSftp getChannel(Ftp ftp){
        SftpChannel sftpChannel = new SftpChannel();
        ChannelSftp channelSftp = null;
        try {
            channelSftp = sftpChannel.getChannel( ftp.getHost(), ftp.getPort(),
                    ftp.getUsername(), ftp.getPassword(), 60000 );
            Pair<SftpChannel, ChannelSftp> pair = new Pair<>(sftpChannel, channelSftp);
            map.put(ftp.getUserId(), pair);
        } catch (JSchException e) {
            logger.error(e.getMessage());
        }
        return channelSftp;
    }

    public static ChannelSftp getSlaveChannel(Ftp ftp){
        SftpChannel sftpChannel = new SftpChannel();
        ChannelSftp channelSftp = null;
        try {
            channelSftp = sftpChannel.getChannel( ftp.getHost(), ftp.getPort(),
                    ftp.getUsername(), ftp.getPassword(), 60000 );
            Pair<SftpChannel, ChannelSftp> pair = new Pair<>(sftpChannel, channelSftp);
            map.put(ftp.getUserId() + GeneralConstant.STANDBY, pair);
        } catch (JSchException e) {
            logger.error(e.getMessage());
        }
        return channelSftp;
    }

    public static ChannelSftp getChannel(String userId){
        Pair<SftpChannel, ChannelSftp> pair = map.get(userId);
        return pair == null ? null : pair.getValue();
    }

    public static void quit(String userId){
        if(!map.containsKey(userId))
            return;

        Pair<SftpChannel, ChannelSftp> pair = map.get(userId);
        SftpChannel sftpChannel = pair.getKey();
        ChannelSftp channelSftp = pair.getValue();
        if(channelSftp.isConnected()){
            channelSftp.quit();
        }
        try {
            sftpChannel.closeChannel();
        } catch (Exception e) {
            logger.error(e.getMessage());
        }
    }

}